Bottom Line:
In animals, low levels of vitamin D are associated with estrus cycle disturbances, but there are virtually no human data.After controlling for age, race, BMI, education, age of menarche, current smoking, alcohol use, and physical activity, a decrease in 25(OH)D of 10 ng/mL was associated with 1.9 times the odds of irregular cycles (Odds ratio (OR) (95% confidence interval (CI)): 1.9 (1.0, 3.4), p=0.04). 25(OH)D was not associated with the occurrence of short cycles (OR(CI): 1.08 (0.79, 1.48, p=0.6) or long cycles (OR(CI): 1.31 (0.66, 2.60), p=0.4).Lower levels of 25(OH)D were associated with irregular cycles, but not with short or long cycles.

Background: In animals, low levels of vitamin D are associated with estrus cycle disturbances, but there are virtually no human data. We examined the association of 25-hydroxyvitamin D (25(OH)D) (a biomarker for vitamin D status) with menstrual cycle characteristics.

Methods: Women aged 35-44 were randomly selected from a Washington D.C. health plan and invited to participate in the Uterine Fibroid Study (1996-1999). Our analysis includes 636 women (57% were African-American) who provided a blood sample and completed a telephone interview that included gynecologic history. Women were asked their usual cycle length in the preceding year. Women who reported it was "too irregular to estimate" were classified as having irregular cycles (N=48). Women were excluded if they currently or recently used hormonal contraception or any other medication that influences menstrual cycles. 25(OH)D was measured by radioimmunoassay in stored plasma samples.

Conclusions: Lower levels of 25(OH)D were associated with irregular cycles, but not with short or long cycles. Vitamin D may play a role in regulating ovulatory function. Further investigation of potential mechanisms is warranted.

Fig1: Flowchart depicting the number of women in the Uterine Fibroid Study included in the analysis of 25(OH)D and menstrual cycle length.

Mentions:
Vitamin D status was quantified through the measurement of the circulating metabolite 25-hydroxyvitamin D (25(OH)D) in stored plasma samples. 25(OH)D is a widely accepted biomarker for vitamin D [11]. 25(OH)D was measured by radioimmunoassay [12] with a method developed at a laboratory that has been certified by the international Vitamin D External Quality Assessment Scheme, and had been for over 10 years. The antibody was generated by the lab, and was co-specific for both 25(OH)D2 and 25(OH)D3. The intra- and interassay coefficients of variation based on blind replicates were 7.6% and 10.6%, respectively. One hundred and four women were missing a 25(OH)D measurement, mostly due to a lack of available blood sample, leaving 642 (Figure 1).Figure 1

Fig1: Flowchart depicting the number of women in the Uterine Fibroid Study included in the analysis of 25(OH)D and menstrual cycle length.

Mentions:
Vitamin D status was quantified through the measurement of the circulating metabolite 25-hydroxyvitamin D (25(OH)D) in stored plasma samples. 25(OH)D is a widely accepted biomarker for vitamin D [11]. 25(OH)D was measured by radioimmunoassay [12] with a method developed at a laboratory that has been certified by the international Vitamin D External Quality Assessment Scheme, and had been for over 10 years. The antibody was generated by the lab, and was co-specific for both 25(OH)D2 and 25(OH)D3. The intra- and interassay coefficients of variation based on blind replicates were 7.6% and 10.6%, respectively. One hundred and four women were missing a 25(OH)D measurement, mostly due to a lack of available blood sample, leaving 642 (Figure 1).Figure 1

Bottom Line:
In animals, low levels of vitamin D are associated with estrus cycle disturbances, but there are virtually no human data.After controlling for age, race, BMI, education, age of menarche, current smoking, alcohol use, and physical activity, a decrease in 25(OH)D of 10 ng/mL was associated with 1.9 times the odds of irregular cycles (Odds ratio (OR) (95% confidence interval (CI)): 1.9 (1.0, 3.4), p=0.04). 25(OH)D was not associated with the occurrence of short cycles (OR(CI): 1.08 (0.79, 1.48, p=0.6) or long cycles (OR(CI): 1.31 (0.66, 2.60), p=0.4).Lower levels of 25(OH)D were associated with irregular cycles, but not with short or long cycles.

Background: In animals, low levels of vitamin D are associated with estrus cycle disturbances, but there are virtually no human data. We examined the association of 25-hydroxyvitamin D (25(OH)D) (a biomarker for vitamin D status) with menstrual cycle characteristics.

Methods: Women aged 35-44 were randomly selected from a Washington D.C. health plan and invited to participate in the Uterine Fibroid Study (1996-1999). Our analysis includes 636 women (57% were African-American) who provided a blood sample and completed a telephone interview that included gynecologic history. Women were asked their usual cycle length in the preceding year. Women who reported it was "too irregular to estimate" were classified as having irregular cycles (N=48). Women were excluded if they currently or recently used hormonal contraception or any other medication that influences menstrual cycles. 25(OH)D was measured by radioimmunoassay in stored plasma samples.

Conclusions: Lower levels of 25(OH)D were associated with irregular cycles, but not with short or long cycles. Vitamin D may play a role in regulating ovulatory function. Further investigation of potential mechanisms is warranted.